In this article we will discuss about the hydrologic cycle of water with the help of a suitable diagram.
Hydrology is the science which deals with movement of the water on the ground, under the ground, evaporation from the land and water surfaces, and transpiration from the vegetation. It also deals and includes the way of going back the water to the atmosphere from where it precipitates.
The water which goes in atmosphere by evaporation and transpiration and again comes back in the form of precipitation under favourable climatic conditions is known as hydrologic cycle. Fig. 2.1 illustrates the hydrologic cycle of water. Due to sun’s heat the water from the earth’s surfaces, lakes, rivers, sea etc. evaporates and rises upwards.
At the high altitude due to reduction in the atmospheric pressure these water vapours expand by absorbing energy from the surrounding air, which cools down. The capacity of the atmosphere at the high altitude depends on its temperature and moisture content. When it falls below the due point, it cannot retain the excessive moisture, which starts falling in the form of rain, hails, dew sleet, frost or precipitation.
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When the temperature falls too much, it may cause snowfall which is also a form of precipitation. Various factors such as temperature, atmospheric pressure, velocity of wind, height of mountains in the region, presence of forests, position of land and water areas etc. and their complex relations are responsible for the precipitation. This precipitating and evaporation processes continue forever and a balance is maintained between the two by nature.